1. Field of the Invention
This invention relates to storage systems, and more specifically to creating an object-level snapshot in a storage system.
2. Description of the Related Art
A storage device (e.g., magnetic disks) typically stores data on a block basis. However, an object-based storage device (OSD) stores data as an object. In an OSD, each object includes the data and an attribute portion. The attributes may include information regarding, for example, the size of the data, user ID information, etc. Since the attribute maintains the size of data in the object, the object size may be variable. In contrast, in current storage devices such as hard disk drives (HDDs) the size of the stored information is typically fixed.
Current snapshot mechanisms are based on block level addressing on a storage system. A file system on a host computer can translate a file name into an appropriate block address. However, objects in an object-based storage device are identified by their object ID (OID), therefore, a snapshot copy on an object-based storage system may require the host computer to manage the relationship between file names and snapshot object OIDs. Further, currently an OSD does not have a copy operation interface. Therefore, when a snapshot copy is provided on an object-based storage system, a new command, or some module that takes care of the snapshot creation operation, needs to be provided in the storage system.
Therefore, there is a need to provide a snapshot copy on an object-based storage system.